The present invention relates to a biosolids and fly ash composition used to condition soil while ameliorating off-gassing of noxious odors.
The disposal of biosolids or sewage sludge, has been a problem for many years. Various techniques have been proposed for disposing of the biosolids as an agricultural fertilizer. While this has certain advantages, the primary disadvantage is that the biosolids tends to off-gas noxious odors which renders this technique unacceptable in populated areas.
The stabilization of biosolids with fly ash has been proposed for use in cement products. U.S. Pat. No. 4,028,130 discloses a method of treating biosolids to form a stable particulate structure that can be deposited in landfills in an environmentally acceptable manner. Biosolids stabilization techniques suffer from the disadvantage of requiring equipment and energy to stabilize the biosolids before being carted off to a disposal site.
It has been known for a long time to use lime to disinfect and deodorize human waste. U.S. Pat. No. 4,902,431 states that this has been known since Roman times. The patent discloses the mixture of kiln dust with biosolids for use as an agricultural fertilizer. The patent notes that “lime stabilizations have the advantage of being low in cost and simple in operations; however, lime addition does not make sludges chemically stable. The patent states that if the pH drops below 11.0, biological decomposition will produce noxious odors.
U.S. Pat. No. 5,454,849 issued Oct. 3, 1995 discloses the mixture of two nuisance waste products, namely sewage sludge ash and water treatment lime for placement on agricultural soils to enhance the nutrient value of the soil and raise the pH for improving plant growth. The patent discloses the application of the mixture in liquid form onto the soil. The patent teaches the burning of the sewage sludge to form an ash which, in turn, is mixed with spent water treatment lime.
U.S. Pat. No. 4,306,978 discloses historical use of lime to treat nuisance conditions such as those resulting from open pit privies. The patent goes on further to note that prior to 1970, very little quantitative information and technical data were available on the reaction of lime with sludge for stabilization and disposal purposes. The patent cites an EPA study that “concludes that lime stabilization has been demonstrated to effectively eliminate odors, improve bacterial and pathogenic organism control, provide stable material for application of agricultural land, . . . . ” In the patented process, sludge is dewatered to produce a sludge cake which is reacted with calcium oxide to produce stabilized sludge pellets.
U.S. Pat. No. 4,554,002 discloses the mixing of kiln dust with waste sludge to produce a disintegratable product which can be applied to land as a soil conditioner. The patent suggests the use of fly ash in “small quantities” to adjust the pH of the material. The patent states that the blending of kiln dust, a high lime product, with sludge, greatly reduces offensive odors at the treatment plant, in transit, and on the field.